Joey Greco is in a better position than most to answer this. After a decade of hosting US hit show Cheaters, which busies itself revealing love rats live on TV, he has experienced more than 800 case studies of people doing the romantic dirty. As he says, “Nothing surprises me any more.”

Les Dennis was famously cuckolded by then wife with fellow actor Neil Morrissey

Here are his five top giveaways for spotting your partner may have found cuddles elsewhere:

1. The obvious stuff – a password going on the mobile phone, disappearing into another room to make or receive calls. The mobile phone has become a modern metaphor for communicating – the phone, these days, is where the heart is.

2. Similarly, papers no longer get left around, emails get shut down abruptly. People get protective over credit card bills, billing information – they’re creating a bubble around themselves.

3. Do they dress and groom (Greco is from Dallas, hence 'groom') differently? If I’m always asking you if I look ok (Greco himself is impeccably ‘groomed’ and toned as befitting a US television figure), then it’s not out of character, but if I’m suddenly telling you I want to lose weight, I want to look better, I want to be more hip, then the chances are I’ve caught the eye of someone new.

4. Bedroom technique. If, after a long time, someone’s got a new ‘skillset’, then this could indicate they’re getting tutelage elsewhere. Ewww.

5. Are you receiving unexpected gifts? Is someone, otherwise unattentive, suddenly lavishing you with expensive presents? Or being overly interested in you? his is delicate, but these could be compensatory moves, designed to make the person feel less guilty. Or it could signal the end of a dalliance, when they’ve decided to commit themselves afresh to you… Probably because they got the heave-ho from someone else, adds Greco, shaking his head.

However, it’s not all bad news from this veteran betrayal consultant. Greco, who isn’t just a TV presenter who fell into this shady business, but has a background in psychology, and continues to believe the best in people. And he has five more tips for healing a relationship that may have suffered the ravages of betrayal or, if possible, preventing it in the first place.

“If you’ve only been in it a couple of months,” he says first, “and they cheat on you… come on, you haven’t got too much invested, move on.”

But if you really want it to work, then…

1. Know how to forgive. And I mean properly. Because people often say they have, but they can harbour things for years.

2. Communicate effectively. Address one another respectfully, whether it’s bad news or good news, so you can develop trust again, and you know someone isn’t trying to break you down.

3. Don’t let someone take your place. Be the person who comments on how your partner looks, how hard they’re working. If you support them with compliments, humour, stimulation, then when someone else comes along and says ‘you’re looking nice today’, it stays just that – a compliment. If they haven’t been hearing that from you, then there’s a gap, and one compliment can be all that’s needed to fill it. Suddenly, they’re going to lunch at the same time at the same place every week, to get another fix of attention, and eventually…

4. It’s easy to say ‘be confident’, but to ‘be complete’ is probably more accurate. It’s romantic to say ‘you complete me’ but that doesn’t happen outside films. Two complete people together will make an interesting relationship. Plus, the more confident and healthy your self-esteem, the more likely you are to flag up things you don’t agree with. Don’t be scared to rock the boat.

5. Always trust your instinct, but not yours fears. Restore your emotional connection. In life, things are either being created or being dissolved. Choose whether you are working to create something, or allowing it to dissolve.

There… easy when you know how.

So, what’s the aim of the show if it’s not just shameless car-crash telly, glorifying in the narrative glee of human disasters? Under Greco’s noble watch, it seems not…

“The way I look at it, we’re getting to stick up who’s been taken advantage of. There’s now legislation in the States to make bullying illegal, and to make someone criminally liable – I can bully someone physically, but I can also do that emotionally. And I want to stick up for someone who doesn’t have a voice.”

Is infidelity a deal-breaker? Greco says no.

“If it were a deal breaker, there wouldn’t be happy couples who have worked through it. So can I believe that it can be resolved? Absolutely, because otherwise what kind of society would we be? Thank god instead we have the capacity as humans to move on and be better people.

Poor old Greco – surely he can’t have any faith left in his own relationships after sitting through all this lot?

“I cannot sit here and say that I’m unaffected. But you still want to see the good in people.”

Finally, who cheats more – men or women?

“We’re equal opportunities. Don’t believe surveys – after hundreds of cases, I can say it’s right down the middle. And some women whom we’ve gone after in a previous series, turn up and they’re the ones being cheated on this time around. What does that tell you? Nothing surprises me.”

The 12th season of Cheaters is on Really, a UKTV channel (Sky 248, Virgin 267, Freeview 20) weeknights at 11pm.